Tank retaining system

ABSTRACT

A retaining system in which straps are provided with hooks that remain engaged with retaining loops even when tension on the straps is released and in which the tightening mechanism includes rods which are located partially below a rib surface on which the straps are placed such that the ends of the rods are near the plane of the strap ends, thereby greatly reducing the bending moment applied to the strap ends and threaded rods. The hook preferably includes a cavity opposite the hook end that will engage the retaining loop when no tension is on the line. In some embodiments, the hook includes a spring-loaded retaining clip to further ensure that the hook does not become disengaged from the retaining loop. The tightening mechanism includes two rods, each of which is positioned to one side of a rib on which the straps rest.

This application is a continuation of U.S. patent application Ser. No.10/135,367, filed May 1, 2002, now U.S. Pat. No. 7,028,967.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to storage tanks generally, and more particularlyto a retainer system for securing a tank to an anchor such as a deadmanor a slab.

2. Discussion of the Background

Underground storage tanks are commonly used for the storage of liquids,including gasoline, other petroleum products, and wastewater. Thesetanks are generally cylindrical in shape, with either curved (e.g.hemispherical) or flat ends. Underground storage tanks may be made ofmany materials, including steel and fiber reinforced plastic (referredto herein as FRP and fiberglass). Such tanks may be single ormulti-walled.

USTs are installed in a wide variety of locations and under a widevariety of conditions. In some locations, the water table is high enoughsuch that some or all of the UST is below the water table. In thesesituations, a buoyant upward force will act on the tank. If the buoyantforce exceeds the downward forces acting on the tank, the tank will‘float’ up out of the ground (referred to herein as flotation). Thissituation is obviously undesirable.

One method commonly used to ensure that flotation does not occur isthrough the use of anchors such as slabs or deadmen. Slabs and deadmenare typically constructed of reinforced concrete. A slab is typicallyseveral inches thick and wider and longer than the corresponding tank. Adeadman is typically 12 to 36 inches wide, 8 to 12 inches high, andusually has a length equal to or greater than the corresponding tank.Deadmen are typically installed on both sides of a tank. A detaileddiscussion of slabs and deadmen, and their use in anchoring undergroundstorage tanks can be found in U.S. Pat. No. 6,467,344, entitled“Underground Storage Tank Buoyancy and Buoyancy Safety FactorCalculation Method and Apparatus,” which is commonly owned by theassignee of the present application and which is hereby incorporated byreference herein.

Tanks are commonly attached to anchors such as slabs and deadmen usingstraps. The straps are commonly used in pairs, with each strap connectedon one end to a hook that is engaged with a loop, or lug, on the anchor.In one embodiment, the other ends of the straps are connected to eachother.

In the past, tightening mechanisms, such as turnbuckles, were typicallylocated at both ends of the straps near the anchor lugs. This tighteningmechanism could not be operated if located at a position where it was incontact with the tank. This arrangement requires installation personnelto enter the excavation pit in which the tanks were located in order toinstall and tighten the straps. This practice was potentially unsafebecause it is possible for excavation sidewalls to collapse unless veryexpensive shoring was used. Additionally, if there was water in thehole, tightening was difficult.

The aforementioned problems with traditional strap systems led XerxesCorporation (“Xerxes”) to develop the “Man Out of the Hole” systemapproximately 15 years ago. In this system, a tightening mechanism wasdeveloped that could be located on top of the tank so that it could beoperated by an installer standing on top of the tank, thereby doing awaywith the need for installation personnel to enter the excavation pitduring installation. This system proved effective and has since beenadopted by a large portion of the industry.

While the original Man Out of the Hole system has been a dramaticimprovement and has generally proven effective, it is not optimal.First, the system requires installation personnel to maneuver the hookend of the strap onto the retaining loop on the anchoring system, and tomaintain tension on the strap once hooked to avoid having the hookdisengage from the anchor retaining loop. This operation requirespatience, and time, especially on the part of inexperienced installationpersonnel. Second, the Man Out of the Hole system uses a threaded rodpositioned above the tank so that the middle of the rod clears the tank.The rod is supported by a pair of brackets, each of which is attached toa strap. A bending force may be created by this elevated rod which meansthat the brackets need to be strengthened to support this force.

What is needed is an improved system that in which the strap hooks aremore easily engaged with the retaining loops and a less expensivetightening mechanism that places less bending force on the brackets, issimple, and cost effective.

SUMMARY OF THE INVENTION

The present invention meets the aforementioned need to a great extent byproviding a retaining system in which straps are provided with hooksthat remain engaged with retaining loops even when tension on the strapsis released and in which the tightening mechanism includes threaded rodswhich are located partially below the rib surface on which the strapsare placed such that the end of the threaded rods or is in or near thesame plane as the strap ends, thereby reducing the bending momentapplied to the brackets. The hook preferably includes a cavity oppositethe hook end that will engage the retaining loop when no tension is onthe line. In some preferred embodiments, the hook further includes aspring-loaded retaining clip to further ensure that the hook does notbecome disengaged from the retaining loop. The tightening mechanismincludes two rods, each of which is positioned to one side of a rib onwhich the straps rest.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantfeatures and advantages thereof will be readily obtained as the samebecome better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIGS. 1 a and 1 b are side views showing a prior art tank/anchorretainer system.

FIG. 1 c is a top view of the retaining system of FIGS. 1 a and 1 b.

FIG. 2 is a partial cross sectional view of the retaining system of FIG.1.

FIG. 3 is a perspective view of a hook according to an embodiment of thepresent invention.

FIG. 4 is a top view of the hook of FIG. 3.

FIG. 5 is a cross-sectional view of the hook of FIG. 3 taken along theline V-V of FIG. 4.

FIG. 6 is a cross-sectional view of a hook according to a secondembodiment of the present invention.

FIG. 7 is a side view of the hook of FIG. 6 engaging a deadman loopprior to tensioning.

FIG. 8 is a side view of the hook of FIG. 6 engaging a deadman loopunder tension.

FIG. 9 is a front view of the hook of FIG. 6 engaging a deadman loopunder tension.

FIG. 10 is a side view of a typical ribbed underground storage tank.

FIGS. 11( a), (b), and (c) are top, side, and end views, respectively,of a strap tensioning system according to an embodiment of the presentinvention.

FIGS. 12( a), (b), and (c) are side, top and end views, respectively ofa strap tensioning system according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be discussed with reference to preferredembodiments of tank/anchor retainer systems. Specific details, such asspecific materials and dimensions, are set forth in order to provide athorough understanding of the present invention. The preferredembodiments discussed herein should not be understood to limit theinvention.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, a sideview of a tank 100 including a prior art Man-Out-Of-The-Hole retainersystem 110 is shown in FIG. 1. The tank 100 is ribbed. The top surfaceof the ribs is indicated in phantom by line 102, while surface of thevalleys between the ribs is indicated by line 104. The retainer system110 includes a pair of fiberglass straps 112 with a hook 114 attached toone end of each of the straps. The hook 114 engages a retaining loop 109provided on the respective deadman 108.

FIG. 2 is a cross sectional view showing the hook 114 engaged with theretaining loop 109 on the deadman 108. The engaging loop 109 istypically a 3/4 inch round steel bar that forms a semicircular arch witheach end of the arch embedded in the deadman 108. The hook 114 willremain engaged with the retaining loop 109 as long as tension ismaintained on the strap 112. However, it is readily apparent that thehook 114 will be disengaged from the retaining loop 109 if tension onthe strap 112 is released as the curved inner surface 115 of the hook114 will not engage the retaining loop 109.

Referring now to FIGS. 1 b and 1 c, it can be seen that the end 113 ofeach strap 112 not attached to hooks 114 is attached to a bracket 140.The two brackets 140 along with the threaded rod 150 form a clamp 160.Each of the brackets 140 includes guides 144 that are adapted tostraddle a rib on which the brackets 140 sit such that the brackets 144remain on the rib. The threaded rod 150 includes a nut 152 on one end.The other end of the threaded rod 150 engages a threaded sleeve 148 suchthat when the nut 152 is turned, relative movement between the brackets144 results. The location of the threaded rod 150 over the top surface102 of the rib results in a bending moment being exerted on the brackets140, which means that the brackets must be strengthened to carry thisload, thereby increasing the cost of the brackets 140.

In practice, tank installers stand on the tank 100 and maneuver thestraps 112 until the hooks 114 engage the retaining loops on the deadmen108. Once this is accomplished, the installers must then line up thebrackets 144 so that threaded rod 150 can be used to apply tension tothe straps 112. It is during this operation that tension may beinadvertently released from the straps 112, thereby allowing hook 114 tobe disengaged from retaining loop 109. When this occurs, the processmust be restarted, which can be frustrating and is wasteful of time,particularly for inexperienced installation personnel.

In contrast to the prior art, the current invention provides a retainingsystem including a hook 300 as shown in FIG. 3 (perspective view) andFIG. 4 (top view). The hook 300 includes a first end 310 and a secondend 320. The first end 310 is the end that engages a deadman retainingloop when the hook 300 is connected to a strap under tension. The hook300 also includes a curved cavity 320 that engages a deadman retainingloop when no tension is on the hook 300 as will be explained furtherbelow. Referring now to FIG. 4, it can be seen that the inner surface350 (shown in phantom in FIG. 4) of first end 310 is curved. The curveis preferably matched to an expected curvature of a deadman loop withwhich the first end 310 is to be engaged when the hook 300 is undertension. The bottom surface 350 of first end 310 is substantially flatin a direction perpendicular to the curvature of the first end 310. Thisis done to help keep the hook 300 upright when it is not under tensionand the outer surface 350 may be resting on a top surface of a deadman.

A cross-sectional view of the hook 300 taken along the line V-V of FIG.4 is illustrated in FIG. 5. The hook 300 includes a cavity 330 intowhich a strap (not shown in FIG. 5) can be inserted. The strap ispreferably formed of fiberglass, but other materials may also be used.The cavity is preferably narrower near its entrance 332 as compared toother portions. When a fiberglass strap (not shown in FIG. 5) isinserted into the cavity 330 and an adhesive (which can also befiberglass) is introduced into the cavity, the adhesive bonds with thefiberglass strap such that the combined thickness of the strap andadhesive is wider than the narrow entrance 332, thereby fastening thestrap to the hook 300 mechanically. The cavity 330 also includes anarrowed neck 334, which functions in the same manner as the narrowentrance 332 to create a second mechanical bond to keep the strapattached to the hook 300.

A cross sectional view (similar to that of FIG. 5) of a hook 600according to a second embodiment of the invention is illustrated in FIG.6. The difference between the hook 600 and the hook 300 of FIGS. 3-5 isthat the hook 600 includes a pivoting, spring-loaded arm 640. The arm640 is pivotable as indicated by the phantom lines in FIG. 6. When inthe open position (indicated by the phantom lines), the arm 640 allowsthe hook 600 to engage a deadman retaining loop (not shown in FIG. 6).When in the closed position, the arm 640 ensures that the hook 600 willnot become disengaged with a deadman retaining loop when the hook 600 isnot under tension. It is preferable for the spring of the spring loadedarm 640 to have a low spring constant such that the arm 640 will openwhen installation personnel attempt to engage the deadman loop with thehook 640 by swinging the hook 600 from an attached strap in apendulum-like manner.

FIG. 7 illustrates the hook 600 engaged with a deadman loop 109. Thereis no tension on the strap 112, so the cavity 320 engages the deadmanloop 109. The arm 640 ensures that the hook 600 does not become freefrom the deadman loop 109. The bottom surface 360 of the first end 310of the hook 600 maintains the hook 600 in an upright position. FIGS. 8and 9 illustrate the hook 600 under tension. The radius of the curvedinner surface 350 of the hook 600 conforms to the radius inner surface109 a of the deadman loop 109.

It should be noted that the height of the deadman loop 109 above the topsurface 108 a of the deadman 108 may vary. However, even if the bottomsurface 360 of the hook 600 is not in contact with the top surface 108 aof the deadman 108, the curved inner surface 350 of the hook 600 willhelp to maintain the hook 600 in an upright position.

A tensioning mechanism according to an embodiment of the presentinvention will now be discussed with reference to FIGS. 10 and 11. FIG.10 is a side view of a typical cylindrical storage tank 100 including aplurality of ribs 101. Each rib includes a top surface 102 and two sidesurfaces 103. Referring now to FIGS. 11( a) and (b), a tensioning system700 is shown in use on the tank 100. The tensioning system includes abracket 740 attached to the ends of the two straps 112. Each bracket 740includes two passages 744 through which pass a threaded rod 150. Thewidth W₁ of the bracket is greater than the width W₂ of the top surface102 of the rib 101. This allows the passages 744 to be arranged suchthat the threaded rods are positioned to the side of the top surface 102rather than over the top surface 102 as in the system of FIG. 1. Thisallows the rods 150 to be positioned at least partially below the topsurface 102 of the rib 101 in approximately the same plane as the strap112, thereby greatly reducing the bending force exerted on the brackets740 as compared to the prior art arrangement illustrated in FIGS. 1( a)and (b).

FIG. 1 c illustrates an end view of the bracket 740. The bracket 740includes two tabs 790 that straddle each side of a rib on tank 100. Thetabs 790 are preferably flared to match the contour of the rib. The tabs790 function to ensure that the bracket 740 does not slip off the topsurface 102 of the rib. The bracket 740 also includes a cavity 112 athat is sized to accept the strap 112. The cavity 112 a is preferablypositioned such that the strap 112 experience little or no bending wheninstalled under tension on the tank.

Each of the passages 744 is flared in the vertical direction asindicated by phantom lines 1101 in FIG. 11( b) but is straight in thehorizontal direction as indicated by phantom lines 1102 in FIG. 11( a).Additionally, the bracket 740 includes a curved surface 742, and awasher 750 has a complimentary curved surface 751. This allows thebracket 740 and the threaded rod 150 to pivot with respect to each otherduring tensioning (which is accomplished by tightening nuts 752).

FIGS. 12( a), (b), and (c) are side, top and end views, respectively, ofanother tensioning system 800 according to the invention that issuitable for use with a tank not having external ribs. The majordifference between the tensioning system 800 and the system 700 of FIG.11 is that the brackets 840 of the system 800 do not include the tabs790 on the brackets 740 of the system 700.

It should be noted that it is possible to use various elements of theinvention with prior art elements. For example, it is possible to usethe hook 600 of FIG. 6 with the prior art tensioning mechanism of FIG.11( b). Similarly, it is possible to use the prior art hook 114 (shownin FIG. 2) with the tensioning system 700 illustrated in FIG. 11. Otherpossible combinations readily apparent.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A method for securing an underground storage tank, the methodcomprising the step of: grasping a first end of a first strap, the straphaving a second end with a first hook attached thereto, the first hookhaving a hook body having a first hooked end for engaging a retainingloop when tension is on the strap, the hook body having a second hookedend opposite the first hooked end for engaging the retaining loop whenthere is no tension on the strap; swinging the second end of the strapsuch that the first hooked end engages a first retaining loop on adeadman; releasing tension on the first strap such that the secondhooked end engages the first retaining loop; repeating the grasping andswinging steps with a second strap such that a second hook on the secondstrap engages a second deadman retaining loop; connecting the first endof the first strap to an end of the second strap opposite the secondhook; and applying tension to the first and second straps to secure theunderground storage tank_(1,) where the first hook further comprises anarm, the arm being pivotally attached to the hook body at a pointopposite the first hooked end, the arm being sized and positioned suchthat the arm is prevented from pivoting in a manner that would result ina distal end of the arm passing the first end.
 2. The method of claim 1,wherein the hook body includes a cavity for accepting the strap, thecavity having a narrow entrance and a first wider interior portion. 3.The method of claim 2, wherein the cavity further includes a narrow neckand a second wider interior portion.
 4. The method of claim 1, whereinthe strap comprises fiberglass.
 5. The method of claim 1, wherein thefirst hooked end has an outside surface, the outside surface beingsubstantially flat in a direction perpendicular to a curvature of thefirst end.
 6. The method of claim 1, wherein the first hooked end has aninside surface, the inside surface being curved in a directionperpendicular to the curvature of the first hooked end.
 7. The method ofclaim 1, wherein the cavity formed by the hook body is curved.